Method of detecting the presence of an insult in an absorbent article

ABSTRACT

A method of detecting the presence of an insult within an absorbent article is disclosed. An electrical property is monitored and the electrical property is compared to a wet/dry threshold value to determine either a wet characteristic or a dry characteristic of the article. If a dry characteristic, then a first and possibly a second test are applied. If a wet characteristic, then the second test is applied. The electrical property is compared to a first threshold value and a second threshold value is set based upon the function of the comparison. A change in the electrical property of the article is monitored to determine if the electrical property has stabilized after activation of an insult alarm.

BACKGROUND OF THE INVENTION

The present invention relates generally to a monitoring system fordetecting the presence of an insult in an absorbent article while it isbeing worn by a wearer.

Disposable absorbent articles find widespread use as personal careproducts such as diapers, children's toilet training pants and otherinfant and child care products, adult incontinence garments and otheradult care products, sanitary napkins and other feminine care productsand the like, as well as surgical bandages and sponges and medicalgarments. These articles absorb and contain body waste and are intendedto be discarded after a limited period of use; i.e., the articles arenot intended to be laundered or otherwise restored for reuse.Conventional disposable absorbent articles comprise an absorbent bodydisposed between an inner layer adapted for contacting the wearer's skinand an outer layer for inhibiting liquid waste absorbed by the absorbentbody from leaking out of the article. The inner layer of the absorbentarticle is typically liquid permeable to permit body waste to passtherethrough for absorption by the absorbent body.

Disposable absorbent training pants, in particular, are useful in toilettraining children. Typically, these disposable undergarments are similarto washable, cloth underwear in the manner in which they are put on andworn, yet provide an absorbent function similar to diapers to maintainskin health. Training pants provide a child undergoing toilet trainingwith an undergarment that eases the transition from diapers to washable,cloth underwear as they become more confident in their ability to usethe toilet independently.

In order to learn to use the toilet independently, a child must firstlearn to recognize when urination has occurred. Because urination mayoften occur during an activity that distracts the child to the extentthat the child does not notice urination, this recognition can representa substantial hurdle in the training process. Also, a child's ability torecognize when urination occurs may be hampered by the improvedperformance of disposable absorbent undergarments which quickly draw andretain urine away from the wearer's skin after an insult occurs.

Close monitoring of a toilet-training child by a caregiver can behelpful in that when urination occurs it can be discussed by the childand caregiver to enhance and improve the learning experience. Therefore,it is beneficial to provide the caregiver with immediate notificationand/or verification that urination has occurred so that it may bediscussed with the child while the event is still fresh in the child'smind.

One way of monitoring a toilet-training child is by using a system thatdetects a change in an electrical property of the undergarment whichelectrical property is a function of the wetness of the undergarment.For example, the electrical property may be resistance, conductance,impedance, capacitance or any other parameter which varies as thewetness of the undergarment varies. For example, pair of spaced apartparallel conductors may be situated within the absorbent material of theundergarment. These conductors are in electrical contact with theabsorbent material of the undergarment and are connected to a sensingcircuit for monitoring the electrical property, the circuit includes apower source, such as a battery. For example, the circuit may comprise avoltage divider for detecting resistance between the conductors. Theoutput of the circuit is an analog output voltage that corresponds to aresistance value. When the undergarment is dry, the resistance betweenthe conductors is extremely high and relatively infinite, appearing asan open circuit. When the undergarment is wet, more particularly whenthe absorbent material of the undergarment between the conductorsbecomes wet, the resistance of the undergarment at that area drops to arelatively lower value because urine acts as a conductor.

Accordingly, in a conventional system a sensor monitors the resistancebetween the conductors and compares resistance values to a predeterminedand fixed threshold resistance value. If a resistance value is less thanthe threshold resistance value, then the sensing circuit (herein sensor)sends a signal to an alarm device, which informs the caregiver and/orthe wearer that the wearer has urinated. For example, the alarm devicemay be a device for producing an auditory signal, such as a song, avisual signal, such as a light, or a tactile signal, such as a change intemperature.

These conventional devices may be prone to giving false positives, thatis informing the caregiver and/or the user that there is urinationpresent in the undergarment when there is not because there is only one“check” or “test” for the presence of urination (i.e., whether theresistance of the undergarment falls below a fixed threshold value).There are situations, such as when the child sits or other pressure isapplied to an undergarment that has been previously insulted, when theresistance of the undergarment may fall below the threshold value, thusindicating a new insult, when in fact a subsequent insult has notoccurred (i.e., detecting a false-positive). Accordingly, conventionaldevices may be ill-suited for accurately detecting multiple insultsand/or preventing the detection of false-positives. Moreover, sweat mayat least somewhat saturate the undergarment, typically over a relativelengthy period of time, and may trigger the sensor. Moreover still,after a first insult of urination by the wearer, the resistance value ofthe undergarment is substantially less than when the product was dry.However, the threshold value has not changed, and therefore, theresistance may be lower than the threshold, thus triggering an alarm,even though a subsequent insult has not occurred.

SUMMARY OF THE INVENTION

In general, a method according to one embodiment of the presentinvention for detecting the presence of an insult within an absorbentarticle comprises monitoring an electrical property of the article asthe article is being worn by a wearer, wherein the electrical propertychanges in response to an insult. The electrical property is compared toa wet/dry threshold value to determine a wet characteristic of thearticle indicating that the article has been previously insulted or adry characteristic of the article indicating that the article is dry andhas yet to be insulted. If the comparing indicates a dry characteristicof the article, then a first test is applied to determine whether aninsult has occurred. If the first test indicates the presence of aninsult, then a second test is applied to the electrical property todetermine whether an insult has occurred. If the comparing indicates awet characteristic of the article, then the second test is applied tothe electrical property to determine whether a subsequent insult hasoccurred.

In another embodiment, the method comprises monitoring an electricalproperty of the article as the article is being worn by a wearer,wherein the electrical property changes in response to an insult. Theelectrical property is compared to a first threshold value. A secondthreshold value is set as a function of the comparison. The electricalproperty is compared to the second threshold value to determine whetheran insult has occurred.

In yet another embodiment, the method comprises monitoring an electricalproperty of the article as the article is being worn by a wearer,wherein the electrical property changes in response to an insult. Theelectrical property is compared to a wet/dry threshold value. A firsttest is applied to compare the electrical property to a first wetnessthreshold. The first wetness threshold is a function of the comparisonof the electrical property to the wet/dry threshold value.

In another embodiment, the method comprises monitoring an electricalproperty of the article as the article is being worn by a wearer,wherein the electrical property changes in response to an insult. Aninsult is determined to be present within the article using theelectrical property. An insult alarm is activated to notify thecaregiver and/or the wearer of the presence of the insult. A change inthe electrical property of the article is monitored to determine if theelectrical property has stabilized. Monitoring the electrical propertyof the article is returned to when the monitored change corresponds tothe electrical property of the article being stable.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side perspective of an article of the present inventionshown in the form of a pair of training pants having a mechanicalfastening system fastened on one side of the training pants andunfastened on the opposite side thereof;

FIG. 2 is a perspective view of the pants of FIG. 1;

FIG. 3 is a perspective view of the pants similar to FIG. 2 showing ahousing of a monitoring system removed from the article;

FIG. 4 is a top plan view of the training pants of FIG. 1 with the pantsin an unfastened, unfolded and laid flat condition, and showing thesurface of the training pants that that faces the wearer when worn andwith portions cut away to show underlying features;

FIG. 5 is cross-sectional view of the pants taken along the planeincluding line 5-5 of FIG. 4;

FIG. 6 is a schematic illustration of the pants and one embodiment of amonitoring system of the present invention;

FIG. 7 is a block diagram for one embodiment of the inventionillustrating an order of operation for components/devices of theinvention, including a measuring device for measuring an electricalproperty of the pants and an analog-to-digital converter for convertingan analog output from a measuring device into digital values to be readby a microprocessor;

FIG. 8 is a block diagram of exemplary instructions for themicroprocessor of the present invention for determining the presence ofan insult using a proportional difference of the measured resistance ofthe pants;

FIG. 9 is a block diagram of exemplary instructions for themicroprocessor of the present invention for determining the proportionaldifference of the measured resistance of the pants using successiveresistance values;

FIG. 10 is a block diagram of exemplary instructions for themicroprocessor of the present invention for determining the presence ofan insult using a rate of change of the measured resistance of thepants;

FIG. 11 is a block diagram of exemplary instructions for themicroprocessor of the present invention for determining the rate ofchange of the measured resistance of the pants using successiveresistance values;

FIG. 12 is a block diagram of devices/components of one embodiment ofthe present invention for determining the rate of change of theresistance of the pants, including a responsive circuit and aconditioning circuit;

FIG. 13 is a block diagram of devices/components of another embodimentthe present invention for determining the rate of change of theresistance of the pants, including a responsive circuit and ananalog-to-digital converter;

FIG. 14 is a schematic of an exemplary responsive circuit in the form ofa differentiator;

FIG. 15 is block diagram of an embodiment of the present inventioncombining the embodiments illustrated in FIGS. 7 and 12 to determine thepresence of an insult in the pants using a proportional difference and arate of change in the resistance of the pants;

FIG. 16 is a block diagram of another embodiment of the presentinvention combining the embodiments illustrated in FIGS. 7 and 13 todetermine the presence of an insult in the pants using a proportionaldifference and a rate of change in the resistance of the pants;

FIG. 17 is a block diagram of instructions for the microprocessor fordetermining whether a measured resistance is either too high or too lowto be an accurate indication of the presence of an insult;

FIG. 18 is a block diagram of the devices/components of anotherembodiment of the present invention for determining whether a measuredresistance is either too high or too low to be an accurate indication ofthe presence of an insult, including a false-positive check circuit;

FIG. 19 is a schematic of an exemplary false-positive check circuit;

FIG. 20 is block diagram of another embodiment of the present inventionillustrating instructions for the microprocessor for determining whetherthe pants are saturated and for allowing the resistance of the pants tostabilize after an insult;

FIG. 20A is a graph illustrating an exemplary resistance profile of apair of pants that has been insulted;

FIG. 21 is a block diagram of another embodiment of the presentinvention illustrating instructions for the microprocessor fordetermining whether the pants are dry, recently insulted, or saturated;

FIG. 22 is a block diagram of another embodiment of the presentinvention similar to the embodiment of FIG. 21 and further includinginstructions for calculating an average magnitude threshold value whenthe pants are recently insulted; and

FIG. 23 is a block diagram of another embodiment of the presentinvention similar to FIG. 22 and further including instructions fordelaying the calculation of the average magnitude threshold value untilthe resistance has stabilized.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings and in particular to FIG. 1, an absorbentarticle of the present invention is representatively illustrated thereinin the form of children's toilet training pants and is indicated in itsentirety by the reference numeral 20. The absorbent article 20 may ormay not be disposable, which refers to articles that are intended to bediscarded after a limited period of use instead of being laundered orotherwise conditioned for reuse. It is understood that the presentinvention is suitable for use with various other absorbent articlesintended for personal wear, including but not limited to diapers,feminine hygiene products, incontinence products, medical garments,surgical pads and bandages, other personal care or health care garments,and the like without departing from the scope of the present invention.

By way of illustration only, various materials and methods forconstructing training pants such as the pants 20 of the various aspectsof the present invention are disclosed in PCT Patent Application WO00/37009 published Jun. 29, 2000 by A. Fletcher et al; U.S. Pat. No.4,940,464 issued Jul. 10, 1990 to Van Gompel et al.; U.S. Pat. No.5,766,389 issued Jun. 16, 1998 to Brandon et al., and U.S. Pat. No.6,645,190 issued Nov. 11, 2003 to Olson et al. which are incorporatedherein by reference.

The pair of training pants 20 is illustrated in FIG. 1 in a partiallyfastened condition. The pants 20 define a longitudinal direction 48 ofthe pants and a lateral direction 49 thereof perpendicular to thelongitudinal direction as shown in FIG. 4. The pants 20 further define apair of longitudinal end regions, otherwise referred to herein as afront waist region, generally indicated at 22, and a back waist region,generally indicated at 24, and a center region, otherwise referred toherein as a crotch region, generally indicated at 26, extendinglongitudinally between and interconnecting the front and back waistregions 22, 24. The front and back waist regions 22, 24 comprise thoseportions of the pants 20, which when worn, wholly or partially cover orencircle the waist or mid-lower torso of the wearer. The crotch region26 generally is that portion of the pants 20 which, when worn, ispositioned between the legs of the wearer and covers the lower torso andcrotch of the wearer. The pants 20 also define an inner surface 28 thatfaces toward the wearer when the pants are being worn, and an outersurface 30 opposite the inner surface. With additional reference to FIG.4, the pair of training pants 20 has a pair of laterally opposite sideedges 36 and a pair of longitudinally opposite waist edges (broadly,longitudinal ends), respectively designated front waist edge 38 and backwaist edge 39.

In the embodiment of FIGS. 1-4, the training pants 20 comprise agenerally rectangular central absorbent assembly, generally indicated at32, and side panels 34A, 34B formed separately from and secured to thecentral absorbent assembly. The side panels 34A, 34B are permanentlybonded along seams to the central absorbent assembly 32 in therespective front and back waist regions 22 and 24 of the pants 20. Moreparticularly, the front side panels 34A can be permanently bonded to andextend transversely outward beyond side margins 47 of the absorbentassembly 32 at the front waist region 22, and the back side panels 34Bcan be permanently bonded to and extend transversely outward beyond theside margins of the absorbent assembly at the back waist region 24. Theside panels 34A and 34B may be bonded to the absorbent assembly 32 usingattachment means known to those skilled in the art such as adhesive,thermal or ultrasonic bonding.

The front and back side panels 34A and 34B, upon wearing of the pants20, thus comprise the portions of the training pants 20 which arepositioned on the hips of the wearer. The front and back side panels 34Aand 34B can be permanently bonded together to form the three-dimensionalconfiguration of the pants 20, or be releasably connected with oneanother such as by a fastening system 59 of the illustrated aspects. Asis known in the art, the side panels 34A, 34B may comprise elasticmaterial or stretchable but inelastic materials.

The absorbent assembly 32 is illustrated in FIGS. 1-3 as having arectangular shape. However, it is contemplated that the absorbentassembly 32 may have other shapes (e.g., hourglass, T-shaped, I-shaped,and the like) without departing from the scope of this invention. It isalso understood that the side panels 34A, 34B may instead be formedintegrally with the absorbent assembly 32 without departing from thescope of this invention.

As shown best in FIGS. 4 and 5, the absorbent assembly 32 comprises anouter cover 40 and a bodyside liner 42 attached to the outer cover 40 ina superposed (opposed) relation therewith by adhesives, ultrasonicbonds, thermal bonds, pressure bonds, or other conventional techniques.The liner 42 is suitably joined to the outer cover 40 along at least aportion of the longitudinal ends of the pants 20. In addition, the liner42 is suitably joined to the outer cover 40. The liner 42 is suitablyadapted, i.e., positioned relative to the other components of the pants20, for contiguous relationship with the wearer's skin during wear ofthe pants. The absorbent assembly 32 also comprises an absorbentstructure 44 disposed between the outer cover 40 and the bodyside liner42 for absorbing liquid body exudates exuded by the wearer and a surgemanagement layer 45 disposed between the absorbent structure and thebodyside liner. A pair of containment flaps 46 are secured to thebodyside liner 42 for inhibiting the lateral flow of body exudates.

With the training pants 20 in the fastened position as partiallyillustrated in FIG. 1, the front and back waist regions are connectedtogether by the fastening system 48 to define the three-dimensionalpants configuration having a waist opening 50 and a pair of leg openings52. The front and back waist edges 38 and 39 (e.g., longitudinal ends)of the training pants 20 are configured to encircle the waist of thewearer to define the waist opening 50 (FIG. 1) of the pants.

As illustrated in FIG. 4, a flap elastic member 53 can be operativelyjoined with each containment flap 46 in any suitable manner as is wellknown in the art. Suitable constructions and arrangements for thecontainment flaps 46 are generally well known to those skilled in theart and are described in U.S. Pat. No. 4,704,116 issued Nov. 3, 1987 toEnloe, which is incorporated herein by reference.

To further enhance containment and/or absorption of body exudates, thetraining pants 20 may comprise a front waist elastic member 54 (FIG. 1),a rear waist elastic member 56, and leg elastic members 58 (FIGS. 2-4),as are known to those skilled in the art. The flap elastic members 53,the waist elastic members 54 and 56, and the leg elastic members 58 canbe formed of any suitable elastic material that is well known to thoseskilled in the art.

The fastening system 80 of the illustrated embodiment compriseslaterally opposite first fastening components 60 adapted forrefastenable engagement to corresponding laterally opposite secondfastening components 62. In one embodiment, a front or outer surface ofeach of the fastening components 60, 62 comprises a plurality ofengaging elements. The engaging elements of the first fasteningcomponents 60 are adapted to repeatedly engage and disengagecorresponding engaging elements of the second fastening components 62 toreleasably secure the pants 20 in its three-dimensional configuration.The fastening components 60, 62 can comprise any refastenable fastenerssuitable for absorbent articles, such as adhesive fasteners, cohesivefasteners, mechanical fasteners, or the like. Suitable fastening systemsare also disclosed in the previously incorporated PCT Patent ApplicationWO 00/37009 published Jun. 29, 2000 by A. Fletcher et al. and thepreviously incorporated U.S. Pat. No. 6,645,190 issued Nov. 11, 2003 toOlson et al.

The outer cover 40 suitably comprises a material that is substantiallyliquid impermeable. The outer cover 40 may comprise a single layer ofliquid impermeable material, or more suitably comprise a multi-layeredlaminate structure in which at least one of the layers is liquidimpermeable. While it is not a necessity for the outer layer to beliquid permeable, it is suitable that it provides a relativelycloth-like texture to the wearer. Alternatively, the outer cover 40 maycomprise a woven or non-woven fibrous web layer that has been totally orpartially constructed or treated to impart the desired levels of liquidimpermeability to selected regions that are adjacent or proximate theabsorbent structure. The outer cover 40 may also be stretchable, and insome embodiments it may be elastomeric. Reference is made to U.S. Pat.No. 5,883,028, issued to Morman et al., U.S. Pat. No. 5,116,662 issuedto Morman and U.S. Pat. No. 5,114,781 issued to Morman, all of which arehereby incorporated herein by reference, for additional informationregarding suitable outer cover materials.

The bodyside liner 42 is suitably compliant, soft-feeling, andnon-irritating to the wearer's skin. The bodyside liner 42 is alsosufficiently liquid permeable to permit liquid body exudates to readilypenetrate through its thickness to the absorbent structure 44. Thebodyside liner 42 may also be stretchable, and in some embodiments itmay be elastomeric. Reference is made to U.S. patent application Ser.No. 09/563,417 filed on May 3, 2000 by Roessler et al., U.S. patentapplication Ser. No. 09/698,512 filed on Oct. 27, 2000 by Vukos et al.,both of which are incorporated by reference herein, for additionalinformation regarding bodyside liner material.

The absorbent structure 44 is disposed between the outer cover 40 andthe bodyside liner 42, which can be joined together by any suitablemeans such as adhesives, ultrasonic bonds, thermal bonds, or the like.While the illustrated absorbent structure 44 is shown and describedherein as extending from the crotch region 26 into both the front andback waist regions 22 and 24, it is contemplated that the absorbentstructure may extend from the crotch region into only the front waistregion, or only the back waist region, without departing from the scopeof this invention.

The absorbent structure 44 is suitably compressible, conformable,non-irritating to a wearer's skin, and capable of absorbing andretaining liquids and certain body wastes. For example, the absorbentstructure 44 may comprise cellulosic fibers (e.g., wood pulp fibers),other natural fibers, synthetic fibers, woven or nonwoven sheets, scrimnetting or other stabilizing structures, superabsorbent material, bindermaterials, surfactants, selected hydrophobic materials, pigments,lotions, odor control agents or the like, as well as combinationsthereof.

The materials may be formed into an absorbent web structure by employingvarious conventional methods and techniques known in the art. Forexample, the absorbent structure 44 may be formed by a dry-formingtechnique, an air forming technique, a wet-forming technique, afoam-forming technique, or the like, as well as combinations thereof.Methods and apparatus for carrying out such techniques are well known inthe art. The absorbent structure 44 may alternatively comprise a coformmaterial such as the material disclosed in U.S. Pat. No. 4,100,324 toAnderson, et al.; U.S. Pat. No. 5,284,703 to Everhart, et al.; and U.S.Pat. No. 5,350,624 to Georger, et al.; which are incorporated herein byreference.

Superabsorbent material is suitably present in the absorbent structure44 in an amount of from about 0 to about 90 weight percent based ontotal weight of the absorbent structure. The absorbent structure 44 maysuitably have a density within the range of about 0.10 to about 0.35grams per cubic centimeter. Superabsorbent materials are well known inthe art and can be selected from natural, synthetic, and modifiednatural polymers and materials.

In one embodiment, the absorbent structure 44 may be stretchable so asnot to inhibit the stretchability of other components to which theabsorbent structure may be adhered, such as the outer cover 40 andbodyside liner 42. For example, the absorbent structure may comprisematerials disclosed in U.S. Pat. Nos. 5,964,743, 5,645,542, 6,231,557,6,362,389, and international patent application WO 03/051254, thedisclosure of each of which is incorporated by reference herein.

The surge management layer 45 may be attached to various components ofthe article 20 such as the absorbent structure 44 and/or the bodysideliner 42 by methods known in the art, such as by adhesive, ultrasonic orthermal bonding. The surge management layer 45 helps to decelerate anddiffuse surges or gushes of liquid that may be rapidly introduced intothe absorbent structure 44 of the article 20. Desirably, the surgemanagement layer 45 can rapidly accept and temporarily hold the liquidprior to releasing the liquid into the storage or retention portions ofthe absorbent structure 44. Examples of suitable surge management layers45 are described in U.S. Pat. Nos. 5,486,166; and 5,490,846. Othersuitable surge management materials are described in U.S. Pat. No.5,820,973. The entire disclosures of these patents are incorporated byreference herein.

Optionally, a substantially liquid permeable wrapsheet (not shown) maysurround the absorbent structure 44 to help maintain the integrity ofthe absorbent structure 44.

The training pants 20 of the present invention include a wetnessmonitoring system for detecting the presence of urine (broadly, aninsult) within the pants 20. Although the wetness monitoring system maytake on other configurations, this particular configuration of thesystem monitors an electrical characteristic of the pants and determineswhether the child has urinated in the pants using such electricalcharacteristic. After detection of urine, the system informs a caregiverand/or a child of the presence of the urine by generating an insultalarm. The alarm may be, for example, either an auditory signal, such asa song, or a tactile signal, such as temperature change, or a visualsignal, such as a blinking light. It is understood that the system maycomprise a device for sending a wireless signal to a remote auditory,visual, tactile or other sensory alarm.

In one particularly suitable embodiment, shown best in FIGS. 2-4, oneexample of the wetness monitoring system is generally indicated byreference numeral 70. The monitoring system 70 includes a sensor fordetecting the electrical property (e.g., resistance R) of the article.The sensor includes a pair of spaced apart generally parallel conductorsC1, C2 disposed within the pants 20 that define a monitoring area 74 ofthe pants disposed between the conductors. The conductors C1, C2 may beconstructed of any material that is generally electrically conductive.For example, the conductors may be constructed of metal strips (e.g.,aluminum strips), metal films, coated films, conductive polymers,conductive inks, or conductive threads. Other conductors are within thescope of this invention. The conductors C1, C2 extend longitudinallyfrom the front waist region 22, through the crotch region 26, to theback waist region 24 of the pants 20. As shown best in FIG. 5, theconductors C1, C2 are disposed within the absorbent assembly 32 betweenthe absorbent structure 44 and the surge management layer 45, althoughthe conductors may be disposed at other locations without departing fromthe scope of this invention.

Current i from a current source B (illustrated schematically in FIG. 6)runs through the conductors C1, C2 of the sensor. The current source imay be a direct current source such as a battery (as illustrated), or analternating current source. In the illustrated embodiment, theconductors C1, C2 are electrically connected to the current source byway of electrically conductive snap fasteners 79. Other ways ofelectrically connecting the conductors to the current source are withinthe scope of this invention. As illustrated in FIG. 3, eachcorresponding end of each conductor C1, C2 is connected to a first snapfastener member 79A located in the front waist region 22 of the pants20. Alternatively, the first snap fastener member may be located in theback waist region 24, or other locations on the pants 20. A housing 82that houses the current source i has corresponding second snap fastenerelements 79B for engaging the first snap fasteners 79A and securing thehousing to the pants 20. In addition to the current source i, thehousing 82 of the present embodiment also houses the remainingcomponents of the wetness monitoring system 70 that will be describedhereinafter, although it is contemplated that the housing may includeonly some or none of the remaining components. In the illustratedembodiment the housing 82 is releasably secured to the pants 20 by wayof the snap fasteners 79, although it is understood that the housing maybe permanently secured to the pants without departing from the scope ofthis invention.

A measuring device 85 (FIG. 6) of the sensor measures an electricalproperty of the monitoring area 74 of the pants 20. In one embodiment,the resistance R of the monitoring area 74 of the pants 20 is measured.Because the conductors C1, C2 are spaced apart, current from the currentsource i must pass through the monitoring area 74 to complete thecircuit. As illustrated schematically in FIG. 6, the monitoring area 74acts essentially as a resistor, as indicated by reference character R.When the monitoring area 74 is dry (e.g., before the presence of aninsult), the resistance of the monitoring area is relatively high, forexample, some resistance above 200 kΩ. When the monitoring area 74 iswetted, for example by an insult, its resistance drops, for example, tosome resistance less than 200 KΩ because of the electrically conductivenature of urine.

In another embodiment, the conductance of the monitoring area 74 of thepants 20 is measured. As stated above, urine is electrically conductiveand the article 20, generally is not electrically conductive. Therefore,when the monitoring area 74 of the pants 20 is wetted, its conductanceis greater than when it is dry. Other electrical properties of the pants20, including impedance, may be measured without departing from thescope of this invention.

The measuring device 85 produces an analog output signal (FIG. 6)indicative of the electrical property of the monitoring area 74 of thepants 20. For example, the measuring device 85 can measure a voltagedrop across the monitoring area 74, and produce an analog output signalcorresponding to the voltage drop. The output voltage signal can be usedto determine other electrical properties, such as resistance or current,by performing suitable calculations known in the art or using areference table. For example, as is well known in the art, the voltagedrop is indicative of the resistance of the pants when the current isconstant. Thus, as explained below in further detail, the resistance ofthe pants 20 may be determined using the analog output signal of themeasuring device 85.

In one embodiment of the present invention, a percent difference test isconducted on the measured resistance of the pants 20 to determine thepresence (or lack thereof) of an insult in the pants as the pants arebeing worn by the wearer. In this embodiment, a proportional difference(e.g., a percent difference) in the measured electrical property of themonitoring area of the pants over time is determined, and thisproportional difference is compared with a difference threshold value todetermine if an insult is present in the pants.

In one example of this embodiment, illustrated in FIG. 7, ananalog-to-digital converter 89 receives the analog output signal fromthe measuring device 85 and converts the signal into a digital outputsignal. A microprocessor 93 receives the digital output signal, which isrepresentative of the magnitude of the electrical property (e.g.,resistance) of the pants 20, and analyzes it to determine the presenceof an insult. If the microprocessor 93 detects the presence of aninsult, then it activates the insult alarm 95. The analog-to-digitalconverter 89 is a conventional device for converting analog signals intodigital signal that can be read by a microprocessor. Theanalog-to-digital converter 89 of the present embodiment may be aseparate device or it may be a component of the microprocessor 93. Forillustrative purposes, the electrical property will hereinafter bereferred to as resistance although, as noted above, it may be anyvariable property of the garment which reflects wetness.

FIG. 8 illustrates schematically the instructions of the microprocessor93 for determining the percent difference in the resistance of the pants20 and comparing the percent difference to a difference threshold valueto determine the presence of an insult. At instruction 100 themicroprocessor 93 collects and stores in its memory a first resistancevalue (R1) from the digital output signal. The microprocessor 93 thendelays sampling for a period of time at instruction 102 beforecollecting and storing a second resistance value (R2) at instruction104. The delay may be programmed or may be a function of the samplingrate of the A/D converter 89 and/or the microprocessor 93.

With the stored first and second resistance values (R1, R2), atinstruction 106 the microprocessor 93 subtracts the second value (R2)from the first value (R1) and divides the resulting difference by thefirst value (R1) and multiplies the resulting quotient by 100%. Theresulting value is stored as a difference indicator value (DIV) atinstruction 108.

At instruction 110, the resulting difference indicator value (DIV) isthen compared to a difference threshold value (DTV) to determine if aninsult is present. For example, if the difference indicator value (DIV)is greater than the difference threshold value (DTV) then this isindicative of the presence of an insult. As an example, the differencethreshold value (DTV) may be a value between 10% and 20% (indicating a10% and 20% decrease in resistance), or more particularly, thedifference threshold value may be about 15%. If the comparison of thedifference indicator value to the difference threshold value isindicative of the presence of an insult, then, if there are no otherindicators, the microprocessor 93 activates the insult alarm 95 atinstruction 112 to inform the caregiver and/or the wearer of thepresence of an insult. If, however, the comparison of the differenceindicator value (DIV) to the difference threshold value (DTV) is notindicative of the presence of an insult, then, if there are no otherindicators, the microprocessor 93 is instructed to repeat the abovesteps for determining new difference indicator values and comparing themto the difference threshold value until an insult is indicated.

The percent difference test is meant to be more accurate (that is,detects insults better and detects false-positives less frequently) thanthe conventional magnitude threshold test because the percent differencetest is independent of the magnitude of the resistance of the pantsprior to an insult. The percent difference test focuses on the amount ofchange in the resistance and allows for more accurate detection ofmultiple voids.

As an example, if the resistance changes from 200 KΩ to 50 KΩ, giving adifference indicator value of 75%, and the difference threshold is 20%,then the insult alarm would be activated. As another example, if theresistance changes from 60 KΩ to 50 KΩ, giving a difference indicatorvalue of 17%, and the difference threshold is 20%, then the insult alarmwould not be activated.

In another example of the difference embodiment, the instructions forthe microprocessor 93 may involve determining the percent differencebetween previous successive resistance values compared to a presentvalue, e.g., the difference between a third resistance value (R3) andsecond resistance value (R2) and the third value (R3) and a firstresistance value (R1).

FIG. 9 illustrates schematically the instructions of the microprocessorfor this embodiment. At instruction 116 the microprocessor 93 collectsand stores in its memory a first resistance value (R1) from the digitaloutput signal at a first time. The microprocessor then delays for aperiod of time at instruction 118 before collecting and storing a secondresistance value (R2) at instruction 120. At instruction 122 themicroprocessor 93 delays, and then it collects and stores a thirdresistance value (R3) at instruction 124. With the values stored, themicroprocessor 93 subtracts the second value (R2) from the third value(R3) and divides the resulting difference by the second value (R2) atinstruction 126 to get a percent difference. The percent difference isstored as a first difference indicator value (DIV 1) at instruction 128and compared to the difference threshold value (DTV) at instruction 130to determine if the comparison is indicative of the presence of aninsult.

If the comparison of the first difference indicator value (DIV 1) isindicative of the presence of an insult, then the insult alarm 95 isactivated at instruction 132. If the comparison is not indicative of thepresence of an insult then the microprocessor is instructed at 134 tocalculate a second difference indicator value (DIV 2) by subtracting thefirst value (R1) from the third value (R3) and dividing the differenceby the first value (R1). This second percent difference (DIV 2) isstored as the second difference indicator value (DIV 2) at instruction136. At instruction 138 the second difference indicator value (DIV 2) isthen compared to the difference threshold value (DTV).

If the comparison of the second difference indicator value (DIV 2) tothe difference threshold value (DTV) is indicative of the presence of aninsult, then the insult alarm is activated at the instruction 132. Ifthe comparison is not indicative of the presence of an insult, then themicroprocessor is instructed to repeat the above steps for comparing anew difference indicator value to the difference threshold value untilan insult is indicated.

In the above example, if either the first indicator value (DIV 1) or thesecond indicator value (DIV 2) is below the difference threshold value(DIV), the microprocessor 93 activates the insult alarm 95. It is alsocontemplated that only when both the first indicator value and thesecond indicator value are greater than the threshold value (i.e., bothcomparisons are indicative of the present of an insult) would the alarm95 be indicated. For example, if the first, second, and third values are85 KΩ, 75 KΩ, and 65 KΩ, respectively, then the difference indicatorvalues for R3−R2 and R3−R1 are 13% and 24%, respectively. Assuming thedifference threshold value is 20%, the insult alarm would not beactivated when comparing R3−R2 to threshold value, but would beactivated when comparing R3−R1 to threshold value.

In another embodiment of the present invention, a rate of change test isconducted on the measured electrical property of the pants 20 todetermine the presence (or lack thereof) of an insult. In thisembodiment, a rate of change of the measured electrical property of themonitoring area 74 of the pants 20 over a period of time is determined,and this rate of change is compared with a rate threshold value todetermine if an insult is present in the pants.

In one example of this embodiment, the output signal from the measuringdevice is converted to a digital output signal (via theanalog-to-digital converter 89, for example) and received by themicroprocessor 93 as explained above and shown in FIG. 7. FIG. 10illustrates schematically one example of the instructions of themicroprocessor 93 for determining the rate of change in the resistanceof the pants 20 and comparing the rate of change to a rate thresholdvalue to determine the presence of an insult. At instruction 142 themicroprocessor 93 collects and stores in its memory a first resistancevalue (R1) from the digital output signal at a first time. Themicroprocessor 93 then delays for a period of time at instruction 144before collecting and storing a second resistance value (R2) atinstruction 146. As explained above, the delay is determined by thesampling period of the A/D converter 89 and/or is programmable byinstructions within the microprocessor 93.

With the stored first and second values (R1, R2), the microprocessor 93subtracts the second value from the first value and divides theresulting difference by the sampling period at instruction 148. Theresulting value is stored as a rate indicator value (RIV) at instruction150. At instruction 152, the microprocessor 93 compares the resultingrate indicator value (RIV) to a rate threshold value (RTV) to determineif an insult is present. For example, if the rate indicator value (RIV)is greater than the rate threshold value (RTV) then this is indicativeof the presence of an insult. If the comparison of the rate indicatorvalue to the rate threshold value is indicative of the presence of aninsult, then, if there are no other indicators, the microprocessor 93activates the insult alarm 95 to inform the caregiver and/or the wearerof the presence of an insult at instruction 154. If, however, thecomparison of the rate indicator value to the rate threshold value isnot indicative of the presence of an insult, then, if there are no otherindicators, the microprocessor 93 is instructed to repeat the abovesteps for determining new rate indicator values and comparing them tothe rate threshold value until an insult is indicated.

Like the percent difference test discussed above, the rate of changetest is meant to be more accurate (that is, detects insults better anddetects false-positives less frequently) than the conventional magnitudethreshold test because the rate of change test is independent of themagnitude of the electrical property of the pants and focuses on howquickly the property changes.

For example, if the resistance changes from 200 KΩ to 50 k over a periodof 0.3 seconds, giving a rate indicator value of 450 KΩ/s, and the ratethreshold value is 25 KΩ/s, then the insult alarm would be activated. Asanother example, if the resistance changes from 75 KΩ to 68 KΩ over aperiod of 0.3 seconds, giving a rate indicator value of 21 KΩ/s, and therate threshold value is 25 KΩ/s, then the insult alarm would be notactivated. The drop in resistance of this latter example may be causedby variations within saturated pants, the presence of sweat, or a numberof other causations other than an insult.

As illustrated in FIG. 11, in another example of the rate of changeembodiment, the instructions for the microprocessor may involvedetermining the rate of change between previous successive valuescompared to a present value (e.g., the rate of change between a thirdvalue and second value and a third value and first value). This exampleis substantially similar to the instruction given in FIG. 9 with respectto the percent difference embodiment, except that the first rateindicator value (RIV 1) between third value (R3) and the second value(R2) is determined at instruction 160 and compared to the rate thresholdvalue (RTV) at instruction 162, and the second rate indicator value (RIV2) between third value (R3) and the first value (R1) is determined atinstruction 164 and compared to the rate threshold value (RTV) atinstruction 166.

In another example of the rate of change embodiment (FIGS. 12 and 13)the output signal from the measuring device 85 is fed through aresponsive circuit 165 that produces an analog rate of change signalindicative of the rate of change of the analog output signal from themeasuring device. For example, when the measuring device 85 generates avoltage signal, an operational amplifier, such as a differentiator, maybe used to generate a signal indicative of the rate of change of thevoltage. An exemplary differentiator suitable for use with thisembodiment of the invention is illustrated schematically in FIG. 14. Theinput 169 of the differentiator 167 of FIG. 14 is the analog outputsignal from the measuring device 85, and the output 170 of thedifferentiator is a linear representation of the change in the rate ofchange of the resistance profile.

Referring back to FIG. 12, in one example using the responsive circuit165 of the present embodiment, a conditioning circuit 175 receives theanalog right of change signal from the responsive circuit 165. Theconditioning circuit 175 is a threshold detector determining whether theanalog rate of change signal has a value greater than a value whichcorresponds to the rate threshold value. The conditioning circuit 175produces a positive output voltage (e.g., +5 volts) if the output signalfrom the responsive circuit 165 indicates a rate of change that isgreater than the rate threshold value. Otherwise, the conditioningcircuit 175 produces a different signal such as no signal (e.g., 0volts) or a negative signal. In response to the output from theconditioning circuit 175, the microprocessor 93 recognizes the positivesignal as corresponding to the insult and activates the insult alarm 95whereas the microprocessor ignores the no signal or negative signal.Alternatively, the microprocessor can be programmed to respond to nosignal (e.g., 0 volts) or a negative signal (e.g., −5 volts) to activatethe insult alarm 95.

Referring to FIG. 13, alternatively, in another example using theresponsive circuit 165, an analog-to-digital converter 89 converts theanalog rate of change signal from the responsive circuit into a digitaloutput signal indicative of the rate of change of the resistance of thepants. The microprocessor 93 receives the digital output signal tocollect and store rate indicator values. The stored digital values areindicative of rate indicator values, and the microprocessor 93 comparesthe stored values to the rate threshold value to determine if there isan indication of the presence of an insult in the pants.

In another embodiment, both the percent difference embodiment and therate of change embodiment may be combined into a single embodiment,whereby the insult alarm 95 is activated only if both the comparison ofthe difference indicator value (DIV) to the difference threshold value(DTV) and the comparison of the rate indicator value (RIV) to the ratethreshold value (RTV) are indicative of the presence of an insult.Alternatively, the insult alarm may be activated if either thecomparison of the difference indicator value to the difference thresholdvalue or the comparison of the rate indicator value to the ratethreshold value are indicative of the presence of an insult.

One example of this embodiment (not shown) is a combination of theexamples of FIGS. 8 and 10 (using R2−R1) or FIGS. 9 and 11 (using R3−R2and R3−R1) where the analog output signal from the measuring device isconverted to a digital output signal and the microprocessor isinstructed to compute both the rate indicator values and the differenceindicator values and compare both values to respective threshold valuesto determine the presence of an insult using the digital output signal.

Another example is illustrated in FIG. 15. This example is a combinationof aspects of the embodiments of FIGS. 7 and 12. The analog outputsignal from the measuring device 85 is provided to both ananalog-to-digital converter 89 and a responsive circuit 165. Themicroprocessor 93 uses the digital output signal from theanalog-to-digital converter 89 to compute the difference indicator value(and optionally a second difference indicator value) and determine ifthe comparison of the indicator value(s) to the difference thresholdvalue is indicative of the presence of an insult, as illustrated inFIGS. 8 and 9. As explained above and illustrated in FIG. 12, theconditioning circuit 175 receives the analog rate of change signal fromthe responsive circuit 165 and produces a corresponding output signal tothe microprocessor 93 indicative of the presence of an insult. Asexplained above, the microprocessor 93 may be instructed to activate theinsult alarm 95 if both the percent difference test and the rate ofchange test indicates an insult, or alternatively, the microprocessormay be instructed to activate the insult alarm if either the percentdifference test or the rate of change test indicates an insult.

Yet another example of the present embodiment is illustrated in FIG. 16.This example is a combination of the aspects of the embodiments of FIGS.7 and 13. The analog output signal from the measuring device 85 isprovided to both a first analog-to-digital converter 89A and aresponsive circuit 165. The microprocessor 93 uses the digital outputsignal from the first analog-to-digital converter 89A to compute thedifference indicator value (an optionally a second difference indicatorvalue) and determine if the comparison of the value(s) to the differencethreshold value is indicative of the presence of an insult, asillustrated in FIGS. 8 and 9. As illustrated in FIG. 13, the analog rateof change signal from the responsive circuit 165 is converted into adigital rate of change signal by a second analog-to-digital converter89B. The digital rate of change signal is then sent to themicroprocessor 93, where the microprocessor compares the digital valuesto a rate threshold value to indicate the presence of an insult. Again,depending on the instruction of the microprocessor 93, either the insultalarm 95 is activated when either both the rate of change test and thepercent difference test indicates an insult or when either testindicates an insult.

In another embodiment of the present invention (FIGS. 17 and 18), afalse-positive check is implemented to determine if a measuredelectrical property is either too high or too low to have been caused bythe presence of an insult. For example, if the resistance of the pants20 is very high (e.g., above 5,000 KΩ) then this is may be an indicationthat the sensor has not been properly insulated. As another example, ifthe resistance of the pants is very low (e.g., below 0.5 KΩ) then thisis may be an indication that the conductors inside the pants aretouching, for example, thereby forming a short circuit. Thisfalse-positive check embodiment may be used in combination with anyother embodiment of this invention or with any other embodiment fordetermining the presence of an insult. For example, this embodiment maybe used to check if the determined rate of change and/or the determinedpercent difference are either too high or too low to be true indicationsof the presence of an insult.

In one example, illustrated schematically in FIG. 17, after themicroprocessor 93 determines that the comparison of an indicator value(e.g., difference indicator value, rate indicator value, or magnitudeindicator value) to a respective threshold value is indicative of thepresence of an insult (indicated by reference numeral 180, themicroprocessor, at instructions 182 and 184, respectively, is instructedto determine whether the present resistance value (R) is greater than anupper check value (UCV) or less than a lower check value (LCV). If thepresent resistance value (R) is either greater than the upper checkvalue (UCV) or less than the lower check value (LCV), then themicroprocessor 93 is instructed to repeat the previous operations usinga new resistance value, when applicable. If the present resistance valueis neither greater than the upper check value nor less than the lowercheck value, then the microprocessor 93 is instructed at instruction 188to activate the insult alarm 95, if no other intervening steps arepresent.

In another example of this embodiment (FIG. 18), a false-positive checkcircuit 190 is used to determine whether a resistance value is above orbelow the upper and lower check values, respectively. As illustratedschematically in FIG. 18, the analog output signal from the measuringdevice 85 is sent to the false-positive check circuit 190. The analogoutput signal of the check circuit 190 is indicative of whether thepresent resistance value is above or below the upper and lower checkvalues, respectively. In the particular example of FIG. 18, aconditioning circuit 192 receives the analog output signal of the checkcircuit 190 and produces an output signal to the microprocessor 93indicative of the resistance value being above or below the upper andlower check values, respectively. Alternatively, in another example (notshown), the analog output signal of the check circuit can be convertedinto a digital output signal using an analog-to-digital converter. Inthis example, the microprocessor receives the digital output signal fromthe converter and compares the digital values to the upper and lowercheck values to determine if there is a false positive.

As an example, the check circuit 190 may comprise a window comparatorcircuit, as illustrated in FIG. 19. The check circuit 190 may compriseother types of circuits without departing from the scope of thisinvention. The input 195 of the check circuit 190 is the analog outputsignal from the measuring device 85, and the output 197 of the circuitis indicative of whether the resistance is above or below the upper andlower check values, respectively.

In another embodiment of the present invention, the microprocessor 93 isinstructed to determine when the pants 20 are saturated. Typically, whenthe pants 20 are saturated, by urine for example, a microprocessor maycontinue to indicate the presence of an insult (e.g., continue toactivate the insult alarm) even though the wearer has not producedanother insult. This false-positive is typical when the test orindicator for the presence of an insult is comparing the resistance (orother electrical property) of the pants to a magnitude threshold value,as it typical in conventional monitoring systems. The false-positiveoccurs because the resistance of saturated pants, for example, istypically continuously less then the magnitude threshold value. Thus,according to this embodiment, the monitoring system of the presentinvention informs the caregiver and/or the wearer that the pants aresaturated and that the pants should be changed and the monitoring system(or at least the components of the system within the housing) should beplaced on a new pair of dry pants.

In one example of the present embodiment, the analog output signal fromthe measuring device 85 is converted into a digital output signal andsent to the microprocessor 93, as illustrated in FIG. 7 and explainedabove. Referring to FIG. 20, the microprocessor 93, at instruction 200,collects and stores resistance value (R1) from the digital outputsignal. Although this illustrated embodiment uses an all digitalapproach, it is understood that other examples may also use in part orin whole an analog approach, as would be generally understood by thosein the art. At instruction 202 the microprocessor 93 compares themeasured resistance value (R1) (broadly, the magnitude indicator value)to a magnitude threshold value (MTV) to determine whether the measuredresistance is an indication of the presence of an insult (broadly, afirst test). For example, the microprocessor 93 may be instructed todetermine whether the resistance is less a magnitude threshold value ofbetween about 30 KΩ and 90 KΩ, and more particularly about 55 KΩ. It isunderstood that this first test may be a test other than a magnitudethreshold test without departing from the scope of this invention.

If the comparison is not indicative of the presence of an insult, thenthe microprocessor 93 is instructed to repeat the above steps andcontinue collecting, storing and comparing subsequent resistance valuesuntil the comparison of such to the magnitude threshold value isindicative of the presence of an insult. If the comparison is indicativeof the presence of an insult, then the microprocessor 93 is instructedat 206 to determine whether the last insult alarm 95 (if there was one)was previously triggered within a preset time period. In one example,the microprocessor compares the amount of time that elapsed between thenew insult and the previous insult and compares that amount to a timethreshold value. For example, the time threshold value may be between 90seconds and 300 seconds, and more particularly about 120 seconds. If thelast insult alarm 95 was previously triggered within the preset timeperiod, then the microprocessor 93 activates a saturation alarm atinstruction 208. The saturation alarm is similar to the insult alarm 95except that it notifies the caregiver and/or the wearer that the pants20 are saturated and need to be changed. For example, the saturationalarm may play a different musical tune or make a different sound thanthe insult alarm which informs the caregiver and/or the wearer that thepants are saturated.

If the last insult alarm did not trigger less than a preset time period,then the microprocessor 93 activates the insult alarm 95 at instruction210 to notify the caregiver and/or the wearer of the presence of aninsult. During the activation of the insult alarm 95 the microprocessor93 is instructed to cease determining the presence of an insult (e.g.,comparing resistance values to the magnitude threshold value). The timeof the alarm is stored in the microprocessor's memory at instruction212, and the insult alarm 95 is activated for a period of time, forexample between 15 seconds and 60 seconds. The period of time that theinsult alarm 95 is activated may be a preset time built into themicroprocessor 93 and/or the alarm. Alternatively, the monitoring system70 may comprise of an alarm reset button (not shown), whereby thecaregiver and/or the wearer may push the button to deactivate the alarmat anytime after activation thereof.

After the period of time of the activation of the insult alarm 95, themicroprocessor 93 is instructed to delay further analysis for a periodof time at instruction 214 before restarting its process of determiningthe presence of an insult (e.g., delay comparing resistance values tothe magnitude threshold value). This delay function allows for theresistance profile of the pants to stabilize after the occurrence of aninsult. The example shown in FIG. 20A illustrates the benefit of thedelay. As shown in FIG. 20A, at time T1 (i.e., at about 1.5 seconds) theresistance of the pants drops to about 30 KΩ because of the presence ofan insult. After the initial insult, the resistance slowly increasesover time due to the insult being absorbed and mixing with the absorbentmaterial of the pants. The insult alarm 95 is deactivated (eithermanually by the caregiver or user or by the microprocessor), at time T2(e.g., at about 20 seconds). Without a delay instruction, themicroprocessor 93 would begin comparing the resistance values to thethreshold value immediately after deactivation of the alarm (e.g., attime 20 seconds). Assuming the magnitude threshold value is 55 KΩ, thiswould lead to either a false insult alarm or a false saturation alarmbecause the resistance of the pants at time 20 seconds is 50 KΩ. Theresistance has not had ample time to increase to its stabilization point(around 70 KΩin this example) and is still below the magnitude thresholdvalue. With the present time delay embodiment of this invention,however, the determination of a subsequent insult by the microprocessoris delayed, for example, for 30 seconds after the deactivation of theinsult alarm, thereby allowing the resistance of the pants to increaseto its stabilization resistance (70 KΩ) at time T4 (i.e., 50 seconds).This delay function decreases the chances of the microprocessor 93detecting a false insult or false saturation, thereby making themonitoring system 70 more accurate in detecting insults.

As an example, the microprocessor 93 may be instructed to delay for apreset time period between about 5 seconds and 600 seconds, and moreparticularly between about 10 seconds and about 60 seconds beforerestarting its determination the presence of an insult (e.g., comparingthe present measured resistance to the magnitude threshold value). Thetime delay may be dependant on the length of the period of time of theactivation of the alarm. For example, where the insult alarm 95 isdeactivated manually by the caregiver and/or the wearer (such as by apush button) after 1 second, the time delay may be greater than if thealarm is deactivated after 30 seconds. This aspect of this embodiment ofthe invention is intuitive given the purpose of allowing the resistanceof the pants to stabilize, as stated above.

It is understood that the delay function and the saturation detectionfunction are not codependent functions of the monitoring system of thepresent invention, and an embodiment of the present invention may haveone without the other without departing from the scope of thisinvention.

Referring now to FIGS. 21-23, yet another embodiment of the monitoringsystem of the present invention substantially combines aspects of thepercent difference embodiment illustrated in FIG. 9 and aspects of therate of change embodiment illustrated in FIG. 11 as a second test (e.g.,comparing a first difference indicator value—DIV 1 and a first rateindicator value—RIV 1, both of which are calculated using a thirdresistance and a second resistance, to respective threshold values—DTVand RTV) and a third test (e.g., comparing a second difference indicatorvalue—DIV 2 and a second rate indicator value—RIV 2, both of which arecalculated using a third resistance and a first resistance, torespective threshold values—DTV and RTV) as embodied in instructions 217and 219, respectively. The monitoring system 70 further combines thesaturation indicator and delay function embodiments illustrated in FIG.20, as embodied in instructions 221 and 223, respectively.

In one example of this embodiment, illustrated schematically in FIG. 21,the microprocessor 93 is instructed at instruction 226 to compare apresent resistance value (R3) (i.e., a magnitude indicator value) to awet/dry threshold value (W/DTV) to determine if the pants have beenpreviously insulted and are ready for subsequent sensing, or are stilldry and have not been insulted. Although this illustrated embodimentuses an all digital approach, it is understood that other examples mayalso use in part or in whole an analog approach, as would be generallyunderstood by those in the art. As an example, the microprocessor 93 maybe instructed to determine if the resistance value is above, forexample, 200 KΩ (wet/dry threshold value), which would indicate that thepants are dry and not previously insulted. If the comparison of theresistance value (R3) to the wet/dry threshold value (W/DTV) indicatesthat the pants are dry (e.g., R3 is greater than 200 KΩ), then themicroprocessor 93 is instructed at instruction 228 to determine if thepresent electrical value compared to a magnitude threshold value isindicative of the presence of an insult (broadly, a first test). Forexample, the microprocessor 93 may determine if the present value ofresistance is less than a magnitude threshold of between about 30 KΩ and90 KΩ, and more particularly about 55 KΩ. If the comparison of thepresent resistance value to the magnitude threshold value is notindicative of the presence of an insult, then the microprocessor 93continues collecting, storing and comparing resistance values to themagnitude threshold value looking for a comparison that is indicative ofthe presence of an insult. As illustrated by FIG. 21, the microprocessor93 does not run the wet/dry test again, although doing so would notdepart from the scope of this invention.

If the comparison of the resistance value (R3) to the wet/dry thresholdvalue (W/DTV) at instruction 226 is not indicative of the pants beingdry (i.e., it is indicative of the pants being wet), then themicroprocessor 93 is instructed to skip the first test (embodied ininstruction 228) of comparing the present electrical value to themagnitude threshold value. Typically, after the first insult (i.e.,after the pants have been previously insulted), comparing the resistanceof the pants 20 to a threshold value (i.e., performing the first test)is not beneficial because of the inaccuracies of the test after a firstinsult. However, this test may be beneficial when the pants are dry,which is why the test is performed when it is indicated that the pantsare dry.

If either the comparison of the present resistance value to the dry/wetthreshold value is indicative of the pants being previously insulted andready to detect subsequent voids (e.g., R3<W/DTV) or the pants are dry(e.g., R3>W/DTV) and the comparison of the present value to themagnitude threshold value is indicative of the presence of an insult(e.g., R3<MTV), then the microprocessor runs the second test at theinstruction 217 and possibly the third test at the instruction 219 todetermine the presence of the insult. The second and third tests, whichare explained in detail above, involve determining whether the percentdifference and rate of change between the third and second values areindicative of the presence of an insult (e.g., DIV 1>DTV and RIV 1>DTV)and whether the percent change and rate of change between the third andfirst values are indicative of the presence of an insult (e.g., DIV1>DTV and RIV 1>DTV). If the second test or the third test is indicativeof the presence of an insult, then the microprocessor 93 is instructedto perform the saturation indication test at the instruction 221 andtime delay function at the instruction 223 as explained above andillustrated in FIG. 20 and the present Figure. If neither the secondtest nor the third test is indicative of the presence of an insult, thenthe microprocessor 93 is instructed to run the second test and possiblythe third test again with a new present resistance value (e.g., a fourthvalue), until a present value passes one of the tests.

Another example (FIG. 22) of this embodiment is similar to the exampleillustrated by FIG. 21. This example includes instructions forcalculating a new magnitude threshold value to compare with the presentresistance value if the microprocessor 93 determines that the pants 20have been wetted, and are now detecting subsequent voids. Although thisillustrated embodiment uses an all digital approach, it is understoodthat other examples may also use in part or in whole an analog approach,as would be generally understood by those in the art. As explainedabove, after the pants 20 have been wetted, the resistance of the pantswhen the resistance stabilizes is different from when the pants weredry, and therefore, using the fixed magnitude threshold value (e.g., 55KΩ) may not be beneficial because it may falsely trigger the insultalarm 95. For example, after a first insult, the resistance of the pantsmay stabilize after the initial decrease to a resistance of 50 KΩ. Ifthe microprocessor 93 solely uses a test with a magnitude thresholdvalue being 55 KΩ, then the microprocessor will trigger the insult alarmeven though a subsequent insult has not occurred. Calculating a newthreshold based on the average resistance value of the pants after thefirst insult helps to prevent this occurrence of detecting falsepositives.

FIG. 22 illustrates schematically instructions for the microprocessor 93for performing the above function of calculating a new magnitudethreshold value. Although this illustrated embodiment uses an alldigital approach, it is understood that other examples may also use inpart or in whole an analog approach, as would be generally understood bythose in the art. At instruction 231, the microprocessor compares thepresent resistance value (i.e., a third value) to a wet/dry thresholdvalue (e.g., 200 KΩ) to determine if the pants are wet or dry, asexplained above with reference to the example of FIG. 21. If thecomparison indicates that the pants are dry (e.g., the third value isgreater than 200 KΩ), then the microprocessor 93 is instructed atinstructions 233 and 235, respectively, to set the magnitude thresholdvalue to the predefined value (e.g., 55 KΩ) and compare the presentresistance value to the threshold value to determine the presence of aninsult.

If the comparison indicates that the pants have been wetted (e.g., thethird resistance value is less than 200 KΩ), then the microprocessor 93is instructed at instruction 237 and 235, respectively, to set anaverage magnitude threshold value as the magnitude threshold value andcompare the present resistance value to the magnitude threshold value.The average resistance value at which the resistance in the pants hasstabilized is calculated by the microprocessor 93 at instruction 240after the activation of the insult alarm 95 and the delay period. Atinstruction 237, this average resistance value is multiplied by somepercentage less than 100% to calculate the average magnitude thresholdvalue. For example, the average resistance value may be multiplied by apercent between 50% and 95%, or more particularly, a percent between 80%and 90%.

If the comparison of the present resistance value with the averagedthreshold value is indicative of the presence of an insult, then thesubsequent instructions for the microprocessor are similar to theinstructions of the previous example illustrated in FIG. 21, except thatif the third test (e.g., the comparison of the percent difference andrate change between the third value and first value) is not indicativeof the presence of an insult, then the microprocessor is instructed toreturn to instruction 231 and compare a new resistance value (e.g., afourth value) to a wet/dry threshold value, and compare the new value toan appropriate threshold (i.e., either the fixed magnitude threshold orthe average magnitude threshold).

Yet another example, illustrated schematically in FIG. 23, is similar tothe example given in FIG. 22 and explained above. The present examplefurther includes instructions for delaying the determination of theaverage magnitude threshold value until the resistance of the pants 20has substantially stabilized after an insult. As explained above, afterthe pants 20 have been wetted by an insult, the resistance of the pantscontinues to generally climb over a period of time after the occurrenceof the insult. Thus, it is advantageous to instruct the microprocessor93 to wait to until the resistance of the article has substantiallystabilized before instructed the microprocessor to calculate the averagemagnitude threshold value in order to calculate a more accurate averageof the resistance.

In the present embodiment, change in the electrical property of thearticle 20 is monitored to determine if the electrical property hasstabilized. For example, the monitored change may be a rate of change(determined, for example, in the manner described above), a percentchange, or any other change that is generally indicative of thestabilization of the electrical property of the article. In the exampleillustrated in FIG. 23, after the activation of the insult alarm and thedelay, the microprocessor 93 is instructed at instruction 242 to comparethe percent change of the resistance of the pants to a lower presetpercent (broadly, a lower preset value) to determine if the resistanceis greater than the lower preset percent. The lower preset percent maybe, for example, between −0.1% and −10%, or more particularly, about−5%. The microprocessor may calculate the percent change of theresistance in the same manner as it calculated the percent difference,as illustrated schematically in FIG. 8. That is, the microprocessorcollects and stores a resistance value, delays, then collects and storesa subsequent resistance value. The latter value is subtracted from theformer value and the difference is divided by the former value to get apercent change value. The resistance values collected after theactivation of the insult alarm are used in this calculation. Other waysof calculating a percent change is within the scope of this invention.

If the resistance of the pants 20 is not increasing at a rate greaterthan the lower preset percent (e.g., less than −5%), then themicroprocessor 93 is instructed to delay a preset time period atinstruction 244. For example, the delay period may be between 60 secondsand 300 seconds, and more particularly about 120 seconds. After the timedelay, the microprocessor 93 is instructed at 245 to compare a newpercent change of the resistance that is calculated after the time delayof instruction 244 to the lower preset percent to determine if theresistance is greater than the lower preset percent. If the resistanceis still not increasing at a rate greater than the lower preset percent,then the microprocessor 93 is instructed to activate the saturationalarm.

If the resistance of the pants is increasing at a rate greater than thelower preset percent (e.g., greater than −5%) either before or after thetime delay of instruction 244, the microprocessor 93 is instructed atinstruction 246 to compare the percent change of the resistance to anupper preset percent (broadly, an upper preset value) to determine ifthe percent change is less than the upper preset percent. The upperpreset percent may be, for example, between 1% and 10%, and moreparticularly about 5%. If the percent change is less than the upperpreset percent, then the microprocessor is instructed the instruction240 to begin calculating the average resistance to be used in theaverage magnitude threshold value. That is, after the resistance hasstabilized as indicated by the percent change being greater than thelower preset percent and less than the upper preset percent, themicroprocessor 93 is instructed to begin sampling the resistance andusing the sampled resistance for calculating the average resistance(e.g., average resistance). If the percent change is greater than theupper preset percent, then the microprocessor 93 is instructed tocontinue testing for when the percent change of the resistance is lessthan the upper preset percent, thereby signifying that the resistancehas substantially stabilized. The computed average resistance is storedand used as needed.

It is understood that the exemplary values and range of values, givenfor the above tests/checks, including exemplary values given for thedifference threshold value (DTV), the rate threshold value (RTV), thelower check value (LCV), the upper check value (UCV), the magnitudethreshold value (MTV), the time threshold value for the saturationindicator embodiment, the time delay period, the wet/dry threshold value(W/DTV), and the upper and lower preset percents, are merely examples,and the values and time periods actually employed in the invention maychange, depending on such variables as material characteristics of thepants (especially, at the monitoring area), the type of sensor used, thetype of conductors used, location of the conductors within the pants,user preference, and any other variables affecting the indicator valuesand time periods used in the various tests.

When introducing elements of the present invention or the embodimentsthereof, the articles “a”, “an”, “the” and “said” are intended to meanthat there are one or more of the elements. The terms “comprising”,“including” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions, products,and methods without departing from the scope of the invention, it isintended that all matter contained in the above description and shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

1. A method of detecting the presence of an insult within an absorbentarticle, said method comprising: monitoring an electrical property ofthe article as the article is being worn by a wearer, wherein theelectrical property changes in response to an insult; comparing theelectrical property to a wet/dry threshold value to determine a wetcharacteristic of the article indicating that the article has beenpreviously insulted or a dry characteristic of the article indicatingthat the article is dry and has yet to be insulted; if the comparingindicates a dry characteristic of the article, then applying a firsttest to determine whether an insult has occurred and, if the first testindicates an insult, then applying a second test to the electricalproperty to determine whether an insult has occurred; if the comparingdetermines a wet characteristic of the article, then applying the secondtest to the electrical property to determine whether a subsequent insulthas occurred.
 2. The method as set forth in claim 1 wherein said firsttest comprises comparing the electrical property to a magnitudethreshold value, and wherein said second test comprises at least oneof 1) determining a difference in the electrical property over a periodof time and comparing said determined difference to a differencethreshold value to determine the presence of an insult in the article,and 2) determining a rate of change in the electrical property over aperiod of time and comparing said determined rate of change to a ratethreshold value to determine the presence of an insult in the article.3. The method as set forth in claim 2 further comprising if the secondtest is not indicative of an insult, then applying a third test todetermine whether an insult is present, said third test comprising atleast one of 1) determining a second difference in the electricalproperty over a second period of time and comparing said determineddifference to a difference threshold value to determine the presence ofan insult in the article, and 2) determining a second rate of change inthe electrical property over a second period of time and comparing saiddetermined rate of change to a rate threshold value to determine thepresence of an insult in the article.
 4. The method as set forth inclaim 1 wherein said electrical property is resistance and said wet/drythreshold value is greater than about 200 K Ohms.
 5. A method ofdetecting the presence of an insult within an absorbent article, saidmethod comprising: monitoring an electrical property of the article asthe article is being worn by a wearer wherein the electrical propertychanges in response to an insult; comparing the electrical property to afirst threshold value; setting a second threshold value as a function ofthe comparison; comparing the electrical property to a second thresholdvalue to determine whether an insult has occurred.
 6. The method as setforth in claim 5 wherein the second threshold is based on an average ofavailable previous values or the second threshold is based on a presetvalue if no previous values are available.
 7. The method as set forth inclaim 6 wherein the first threshold value is a wet/dry indicator value,and wherein when the comparison of the electrical property of thearticle to the wet/dry indicator value is indicative of a drycharacteristic of the article, then the second threshold is based on thepreset value, and wherein when the comparison of the electrical propertyof the article to the wet/dry indicator value is indicative of a wetcharacteristic of the article, the second threshold value is based onsaid average of previous values.
 8. The method as set forth in claim 7wherein the electrical property is resistance and the wet/dry thresholdvalue is greater than about 200 K Ohms, and the preset value is between30 K Ohms and 90 K Ohms.
 9. The method as set forth in claim 7 whereinthe threshold hold value when there is a wet characteristic of thearticle is a percentage of the average of the previous values of theelectrical property of the article, said percentage being between about70% and about 90%.
 10. A method of detecting the presence of an insultwithin an absorbent article, said method comprising: monitoring anelectrical property of the article as the article is being worn by awearer wherein the electrical property changes in response to an insult;comparing the electrical property to a wet/dry threshold value; applyinga first test comparing the electrical property to a first wetnessthreshold, said first wetness threshold being a function of thecomparison of the electrical property to the wet/dry threshold value.11. The method as set forth in claim 10 further comprising applying asecond test comparing the electrical property to a second wetnessthreshold, said second wetness test being a function of the comparisonof the electrical property to the wet/dry threshold.
 12. A method ofdetecting and communicating to a caregiver and/or a wearer the presenceof an insult within an absorbent article, said method comprising:monitoring an electrical property of the article as the article is beingworn by the wearer, wherein the electrical property changes in responseto an insult; determining the presence of an insult within the articleusing the electrical property of the article; activating an insult alarmto notify the caregiver and/or the wearer of the presence of the insult;monitoring a change in the electrical property of the article todetermine if the electrical property of the article has substantiallystabilized; and returning to said monitoring of the electrical propertywhen the monitored change in the electrical property corresponds theelectrical property of the article being substantially stable.
 13. Themethod as set forth in claim 12 further comprising activating asaturation alarm if the monitored change in the electrical propertycorresponds to a saturated article.
 14. The method as set forth in claim12 wherein monitoring the change further comprises: determining whetherthe change in the electrical property is between an upper preset valueand a lower preset value, indicating that the electrical property of thepants has substantially stabilized.
 15. The method as set forth in claim13 wherein determining whether the change in the electrical is betweenan upper preset value and a lower preset value comprises: comparing thechange to a lower preset value; if the percent change is less than thelower preset value, then activating a saturation alarm, if the change isgreater than the lower preset value, then comparing the change to anupper preset value, if the change is less than said upper preset value,then returning to said monitoring of the electrical property, if thechange is greater than said upper preset value, then continuing tocompare subsequent changes to the upper preset value until a change isless than said upper preset value.
 16. The method as set forth in claim15 wherein monitoring the change further comprises if the change is lessthan the lower preset value, then delaying for a preset period andcomparing a new change to the lower preset value, and either activatinga saturation alarm if the delayed comparison is less than the lowerpreset value, or comparing the change to the upper preset value if thedelayed comparison is greater than the lower preset value.
 17. Themethod as set forth in claim 15 wherein the monitored change is one of apercent change and a rate of change of the electrical property of thearticle.